The present invention relates to a hand circular saw.
More particularly, it relates to a hand circular saw which has a motor housing accommodating a motor connected with a saw shaft which supports a saw blade, and a base plate, as well as a physical turning axle for inclined or beveled cuts.
Hand circular saws of the above mentioned general type are known in the art. One of such saws is disclosed for example, in the U.S. Pat. No. 3,977,080. It is turnable relative to a base plate about a physical axle extending parallel to the base plate and to the saw blade plane for performing inclined or bevel cuts. The base plate carries on its lower side a throughgoing U-shaped groove. With the groove, the base plate can engage the guiding rib of a guiding rail and move on the guiding rail along its longitudinal edges. Thereby a guided feed for the hand circular saw is possible. For straight cuts, the outer edge of the guiding rail extending normal to the workpiece surface must be positioned near the saw blade. For inclined cuts, approximately 45.degree. cuts the outer edge extending at an acute angle to the workpiece plane must be positioned near the saw blade. These two possible different working positions of the guiding rail for the hand circular saw are produced in that, the guiding ribs of the guiding rail extend parallel to the longitudinal edges but offset relative to the center by a certain distance. This distance corresponds to the half distance of the two engagement lines of 90.degree. to 45.degree.. This distance is produced due to the turning axis located over the upper surface of the workpiece.
The handling of this hand circular saw with the guiding rail is quite complicated. The two different positions of the guide rail relative to the hand circular saw for straight and inclined cuts are easily exchangeable. During the inclined cut the tool can hit the guiding rail and damage the latter or during the straight cut downward clamping action of the edge located near the tool can be lost by excessive distance from the tool.
The desired condition in which a parallel displacement of the tool engagement line does not occur is obtained in that, instead of a physical turning axle a coulisse-like turning guiding means are used. The guiding paths of the turning guiding means have a center of curvature located on the upper surface of the workpiece and virtually defining the turning axis. With the loss of the physical turning axle, the advantage of the special robustness, simple manufacture as well as handling of the hand circular saw are lost.